Connector ferrule with improved seal construction



Nov. 1, 1966 F. B. STARK ETAL CONNECTOR FERRULE WITH IMPROVED SEAL CONSTRUCTION Filed Nov. 24, 1964 IN VENTOR.

ud A! TM Mm B NW R Y F B United States Patent 3,283,287 CGNNECTOR FERRULE WITH IMPROVED SEAL CONSTRUCTION Frank Benjamin Stark, Wormleysburg, and Ronald (Jlair Laudig, Camp Hill, Pa., assignors to AMP Incorporated, Harrisburg, Pa.

Filed Nov. 24, 1964, Ser. No. 413,569 Claims. (Cl. 339-177) This invention relates to an improved sealing means for crimp-type connections.

The practice of crimping a malleable ferrule to terminate the outer braid of coaxial or shielded cable to a connector has come into general usage to replace prior practice of soldering, clamping rings, or the like. The typical approach is to employ a back-up sleeve sufiicrently rigid to preclude deformation in conjunction with a ferrule adapted to fit over such sleeve and over the metallic braid of a cable and to crimp such inwardly to drive the braid into intimate contact with the sleeve. It has also become an accepted practice to provide a ferrule which extends back over the outer insulating sheathing of the cable and to crimp such inwardly a slight amount to provide a mechanical grip of the cable and thus stabilize the interface accomplished by the forward engagement of the ferrule with the connector braid and sleeve.

With the state of the art as above outlined, shortcomings were found as to the entry of moisture, contaminants or the like into the connector. The present invention answers these shortcomings and includes as an object the provision of a connector assembly adapted for use with crimping techniques to provide a moisture and gas-tight seal of a quality not heretofore available.

It is a further object of the invention to provide a sealing means for coaxial connectors and the like which is simple and inexpensive to manufacture and use.

It is another object of the invention to provide a seal for crimp-type connectors which is adapted to become operative responsive to a single crimping operation.

The foregoing objectives are attained through the use of a connector and ferrule assembly carrying a pair of spaced seals arranged to be placed in permanent compression through the deformation of a ferrule in crimping. The invention employs one seal carried by the [ferrule to engage the cable and the other seal carried by an extension of the connector over which the ferrule is placed and crimpe-d.

In the drawings:

FIGURE 1 is a longitudinal view of a coaxial connector having the left end sectioned to show the invention assembly prior to the application of crimping forces;

FIGURE 2 is a view similar to that of FIGURE 1 after the application of crimping forces to effect compression of the seals of the invention;

FIGURE 3 is an enlarged view of the seal and assembly shown in FIGURE 2; and

FIGURE 4 is an enlarged cross-sectional view through lines 44 of FIGURE 2.

Referring now to FIGURE 1, 10 represents a coaxial connector comprised of intermated and engaged connector halves of standard construction each adapted to be terminated to coaxial or shielded cables such as 12. The cable 12 is comprised of an outer sheath 14 of relatively thick insulating and weather-proofing material, a metallic braid 16 surounding a dielectric sheath 18 and a center conductor '20. Cable of this type is widely used in the communication industry in applications calling for signal paths shielded from RFI or for the transmission of signals of higher frequencies. The type of connector represented by 16 adapted for use with such cables is shown in my coice pending application Serial No. 268,873, filed March 29, 1963, now Patent No. 3,212,050.

As a part of each connector half there is provided a nmatallic extension shown as 30, which has an inner bore adapted to receive a dielectric sheath 18 of the cable and the center conductor 20, which is terminated to a connector center contact not shown. The sleeve 30- is made sufliciently thick and rigid to resist deformation during the application of a ferrule under crimping forces and is made of length to provide a substantial zone of interface between the braid 16 and the sleeve outer surface. The outer end of 30 is beveled as at 32 to facilitate insertion beneath the braid 16. At a point along the length of sleeve 30 just to the right of the geometrical center is an outer circular slot shown as 34 adapted to receive and hold a seal shown as 36. The seal 36 has a generally rectangular cross-section and is comprised of a material suitably flexible to be driven in compression during the crimping operation which deforms the ferrule inwardly about the seal and sleeve.

As a further part of the assembly of the invention there is included a ferrule 40 of malleable material having in its undeformed shape a substantial length of constant diameter and ending in an outer flared portion 42, which includes a reverse bend to form a lip 44 to define a recess for accommodating a further seal 46. The seal 46 has in its relaxed state a cross-sectional configuration as indicated in FIGURE 1 and is of material having flexible characteristics permitting the compression of the seal during deformation of the ferrule 40. The seal 46 is such as tobe snapped into the pocket formed by 42, 44 and retained therein.

In use, the cable 12 is first stripped in the manner indicated from FIGURE 1, the ferrule 40 is positioned back on the cable and the braid 16 is worked over the end portion 32 of 30, up to the point of engagement with the training edge of seal 36. In this position ferrule 40 is then pulled forwardly to a point of engagement with the rear end of the connector. A crimp is then applied which is substantially circular as shown in FIG- URE 4 to deform the ferrule 40 inwardly along its length to the configuration shown in FIGURE 2. The crimp.

may be thought of as being comprised of three separate segments shown as I, II and III. The crimp segment I is controlled to result in seal 46 being substantially compressed inwardly against the outer sheath 14 of cable 12, and of course outwardly against the inner portion of the inner surface of 42. The reduction of diameter throughout the length of crimp segment I is made to be less than that which would result in a substantial inward movement of the braid 16 to change the spacing between the inner conductor 20 and the outer conductor formed by the braid. The segment II is driven inwardly to lightly engage the cable along that segment length and lightly compress the outer sheath 14 to mechanically support the cable at a point removed from the zone wherein the connector interface is accomplished. The crimp segment III is driven in more substantially with the radial reduction of diameter being such as to cause the braid 16 to bite into the outer surface of the sleeve 30 bursting the surface oxidation of the conductive strands of the braid and of the interior surface of the ferrule and the outer surface of 30 to form a substantial engage-ment of clean metal. During the application of the crimp to segment III, the seal 36 is substantially compressed down within the recess 34 to be forced against the inner surface of the ferrule and the outer surface of the sleeve.

Viewing now the effect of the seals of the invention, the dotted lines of FIGURE 3 show the paths which moisture or contaminants must follow to enter the connector from the ferrule assembly. In line With each path is a seal under substantial compression extending full around the cable sheath and the sleeve extension. the cable 12 is bent in the manner indicated by the dotted line in FIGURE 13, which frequently may happen in use, the seal 46 through being held under substantial compression will nevertheless result in a maintenance of surfaces in engagement with the outer sheath material. As a further point of advantage it will be observed that both seals are substantially covered by the metallic material of the ferrule and thus protected from damage during use of the connector. The ferrule in combination with the cable sheath and the connector sleeve substantially confines the seal to prevent extremes of temperature from rendering the seals in operative. As a still further advantage, the device of the invention may be stored without the seals becoming deformed by moisture or temperature to make assembly difficult. Since both seals are held in substantial compression in use, any slight production differences or deviations in the seal dimensions are automatically accommodated.

In an actual embodiment, the seals 36 and 46 were comprised of silicone rubber. Numerous elastomers are available having similar characteristics. The ferrule 40 was comprised of silver plated ETP copper. In use the pre-crimped outer diameter dimensions of the ferrule were, in inches:

III-0.223

and the post-crimped dimensions in diameter were:

III0.200

It is to be appreciated that the foregoing description represents a preferred embodiment of the invention and it is fully contemplated that the device of the invention may be utilized with a wide assortment of connectors, splices, terminals and the like, wherein crimping techniques are employed to deform a ferrule to terminate cable.

What is claimed is:

1. In a device of the type adapted to connect coaxial cable the improvement comprising a connector body including a metallic sleeve extension of a thickness to resist deformation during crimping, the said sleeve having a bore adapted to receive the dielectric sheath and center conductor of coaxial cable therein with the outer conductor of such cable over said extension, an annular groove on the outside surface of said extension, 2. first seal of flexible material carried in said groove having a relaxed diameter extending radially beyond the extension surface and down into said groove, a malleable ferrule of a length to cover said extension and a portion of the cable extending out of said extension and of a diameter to fit over said cable outer conductor as positioned on said extension, the said ferrule having an outwardly flared portion defining a recess, a second seal of flexible material carried in said recess and having a relaxed thickness to engage the cable outer surface and the ferrule recess inner surface, whereby upon the application of crimping forces to said ferrule said seals will be driven into substantial compression against the extension and the cable outer surfaces.

2. The device of claim 1 wherein said groove is positioned proximate the longitudinal center of said extension and the said recess is positioned at the outer end of said ferrule.

3;. The device of claim 1 wherein said ferrule recess includes an inwardly extending radial lip to captivate said second seal.

4. In a connection of a coaxial device to coaxial cable an improvement comprising a connector sleeve extension having the cable dielectric sheath and center conductor fitted therein and the cable braid fitted thereover, an annular groove in the outside surface of said extension, at flexible seal member in said groove, a ferrule member extending along said extension and over the braid and seal member, the said ferrule being deformed radially inward to hold the braid and seal member compressed in tight engagement with the extension surfaces, the said ferrule extending outwardly over the cable and having a further flexible seal member fitted thereunder, the ferrule being deformed radially inward to hold said further seal member in tight engagement compressed against the cable outer surface to seal the connection.

5. The connection of claim 4 wherein said ferrule includes an inner recess formed from an outwardly flared portion positioned at the outer end thereof, said recess carrying said further seal member.

6. The connection of claim 4 wherein said ferrule includes a substantial length between the engagement with the seal member, said length being deformed radially inward to grip the cable outer surface.

7. In a seal assembly for electrical connectors the improvement comprising a circular metallic member of rigid construction adapted to receive an electric cable therein, an annular groove in said member and a first seal of compressible material filling said groove and extending outwardly therefrom in its relaxed state, a circular metallic ,ferrule adapted to fi-t over said member and engage the first seal, said ferrule having at one end an outwardly flared portion and a further seal of compressible material carried therein, said further seal in its relaxed state having an inner diameter to engage the cable outer diameter, an outer diameter to engage the ferrule flared portion, the said ferrule being malleable and adapted to be deformed inwardly by a circular crimp to compress the seals against the said member and cable.

8. The assembly of claim 7 wherein the said ferrule includes a further malleable portion extending longitudinally between said seals and adapted to be deformed inwardly by a circular crimp to grip the cable outer surface.

9. In a connection of coaxial cable of the type having a center conductor surrounded by a dielectric sheath, an outer conductor and a protective sheath of flexible material to a coaxial connector having a sleeve extension adapted to receive a ferrule crimped thereover, the improvement comprising a first seal of flexible material secured in a groove in the connector extension, 21 ferrule member having an outwardly extending pocket at its outer end, a second seal fitted in said pocket in engagement with the cable protective sheath and an intermediate portion of substantial length overlying the extension and a portion of said cable, the said ferrule being deformed radially inwardly to compress said first seal against said extension, to compress said second seal against said protective sheath and to cause said intermediate portion to grip said protective sheath.

10. The connection of claim 9 wherein the deformation of the ferrule over said second seal and along said intermediate portion is limited to preclude any substantial change of spacing between the cable conductors.

References Cited by the Examiner UNITED STATES PATENTS 2,862,994 12/1958 Yeiser 339223 X 3,054,981 9/1962 Malek et al. 339177 7 3,212,050 10/1965 Stark 339177 EDWARD C. ALLEN, Primary Examiner.

W. D. MILLER, Assistant Examiner. 

1. IN A DEVICE OF THE TYPE ADAPTED TO CONTACT COAXIAL CABLE THE IMPROVEMENTS COMPRISING AA CONNECTOR BODY INCLUDING A METALLIC SLEEVE EXTENSION OF A THICKNESS TO RESIST DEFORMATION DURING CRIMPING, THE SAID SLEEVE HAVING A BORE ADAPTED TO RECEIVE THE DIELECTRIC SHEATH AND CENTERL CONDUCTOR OF COAXIAL CABLE THEREIN WITH THE OUTER CONDUCTOR OF SUCH CABLE OVER SAID EXTENSION, AN ANNULAR GROOVE ON THE OUTSIDE SURFACE OF SAID EXTENSION, A FIRST SEAL OF FLEXIBLE MATERIAL CARRIED IN SIAD GROOVE, A MALLEABLE A RELAXED DIAMETER EXTENDING RADIALLY BEYOND THE EXTENSION SURFACE AND DOWN INTO SAID GROOVE, A MALLEABLE FERRULE OF A LENGTH TO COVER SAID EXTENSION AND A PORTION OF THE CABLE EXTENDING OUT OF SAID EXTENSION AND OF A DIAMETER TO FIT OVER SAID CABLE OUTER CONDUCTER AS POSITIONED ON SAID EXTENSION, THE SAID FERRULE HAVING AN OUTWARDLY FLARED PORTION DEFINING A RECESS, A SECOND SEAL OF FLEXIBLE MATERIAL CARRIED IN SAID RECESS AND HAVING A RELAXED THICKNESS TO ENGAGE THE CABLE OUTER SURFACE AND THE FERRULE RECESS INNER SURFACE, WHEREBY UPON THE AMPLICATION OF CRIMPING FORCES TO SAID FERRULE SAID SEALS WILL BE DRIVEN INTO SUBSTANTIAL COMPRESSION AGAINST THE EXTENSION AND THE CABLE OUTER SURFACES. 